Results on double beta decay of 82Se with CUPID-0 Phase I.

CUPID-0 is the first neutrinoless double beta decay (0νββ) experiment based on highly enriched scintillating bolometers. It consists in an array of Zn82Se detectors operated at LNGS since 2017. During the Phase I of data taking, concluded at the end of 2018, the experiment collected an exposure of 9.95 kg·yr of ZnSe. The simultaneous heat-light readout provides a powerful rejection of α-particles and allows us to suppress the background in the region of interest down to 3.5−0.9+1.0×10−3 counts/(keV·kg·y), an unprecedented level for this technique. Thanks to this achievement, we set the most stringent lower limit on the 82Se 0νββ half-life. Moreover, we have developed a full background model, which allows us to identify the origin of the events in the region of interest. The reconstruction of the CUPID-0 spectrum has enabled us to perform the most precise measurement of the 2νββ of 82Se. [ABSTRACT FROM AUTHOR]